Garmin 430 installed and Generator light coming on.

[Kitfox43]

Sceniro...............1961 Cessna Skylane with generator. Just installed a Garmin 430. also has a KX 155 nav/com, push to talk on left and right yoke.
Prior to installation no problems, by the way the 430 replaced a KX 175.
Here's the problem.
When using the 430 and you push to talk using the switches on either yoke, the generator light comes on and the amp meter shows a big draw, (needle moves to the left) this occur at all RPM ranges including cruise power. One other thing, the problem seems to exist when using certain comm frequencies. Everything is fine when using the KX 155.
It's at a different radio shop now then did the installation. This is what the new shop has done so far.
Replaced comm antennas and coax. Replaced all wiring going to the 430, checked all pins, checked all grounds, checked antenna coax plug in 430 tray, bypassed amp meter, they've also called Garmin, the 430 prior to installation had been sent to Garmin and completely gone through with a new warranty. Tried a different 430 with same results.
Anyone have any ideas?

 

[Clark1961]

What does the load analysis say?

On another note, a shunt is easy to disturb and get out of whack. An ammeter will show a false reading if the shunt is malfunctioning.

 

[Kitfox43]

If I remember correctly the 430 is using slightly less power to transmit then the KX 155..........what the numbers are, I don't know.

 

[Dan Thomas]

DO you have an electronic voltage regulator in that airplane? A Zeftronics, perhaps? If so, check the com antenna coax grounds at the antennas. Make sure the antenna bases are grounded, too. Electronic regulators are very sensitive to small voltage spikes caused by stray RF getting into the aircraft's electrical system.

Or you might just have maxed out that old generator with one more radio.

 

[Kitfox43]

DO you have an electronic voltage regulator in that airplane? A Zeftronics, perhaps? If so, check the com antenna coax grounds at the antennas. Make sure the antenna bases are grounded, too. Electronic regulators are very sensitive to small voltage spikes caused by stray RF getting into the aircraft's electrical system.

Or you might just have maxed out that old generator with one more radio.

The antenna and coax were replaced, so I'm assuming all is good in that area, since the problem is still there with new antennas and coax. I dont' know if the voltage regulator is electronic or not...........however, they are going to try a different regulator. My understanding is, the 430 is using less power then the radio it replaced. There's some speculation that it might be caused by the generator, possible fix would be replace it with a alternator.

 

[bnt83]

First thing I would do is run the airplane and power the 430 from a source other than the ship's bus. If it is still doing it then it would seem to be some wild RF issue.

 

[Kitfox43]

DO you have an electronic voltage regulator in that airplane? A Zeftronics, perhaps? If so, check the com antenna coax grounds at the antennas. Make sure the antenna bases are grounded, too. Electronic regulators are very sensitive to small voltage spikes caused by stray RF getting into the aircraft's electrical system.

Or you might just have maxed out that old generator with one more radio.

You hit the nail on the head.............finally tracked it down............put the old type regulator on and no more problems. Thanks for the help.